Low contamination high density plasma etch chambers and methods for making the same

ABSTRACT

A plasma processing chamber having a chamber liner and a liner support, the liner support including a flexible wall configured to surround an external surface of the chamber liner, the flexible wall being spaced apart from the wall of the chamber liner. The apparatus can include a heater thermally connected to the liner support so as to thermally conduct heat from the liner support to the chamber liner. The liner support can be made from flexible aluminum material and the chamber liner comprises a ceramic material. The flexible wall can include slots which divide the liner support into a plurality of fingers which enable the flexible wall to absorb thermal stresses.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to the fabrication ofsemiconductor wafers, and, more particularly, to high density plasmaetching chambers having lining materials that reduce particle andmetallic contamination during processing, and associated chamber liningstructures.

[0003] 2. Description of the Related Art

[0004] As integrated circuit devices continue to shrink in both theirphysical size and their operating voltages, their associatedmanufacturing yields become more susceptible to particle and metallicimpurity contamination. Consequently, fabricating integrated circuitdevices having smaller physical sizes requires that the level ofparticulate and metal contamination be less than previously consideredto be acceptable.

[0005] In general, the manufacturing of the integrated circuit devices(in the form of wafers) includes the use of plasma etching chambers,which are capable of etching selected layers defined by a photoresistmask. The processing chambers are configured to receive processing gases(i.e., etch chemistries) while a radio frequency (RF) power is appliedto one or more electrodes of the processing chamber. The pressure insidethe processing chamber is also controlled for the particular process.Upon applying the desired RF power to the electrode(s), the processgases in the chamber are activated such that a plasma is created. Theplasma is thus configured to perform the desired etching of the selectedlayers of the semiconductor wafer.

[0006] Typically, a processing chamber that is used for etchingmaterials such as silicon oxides requires relatively high energies toachieve the desired etch result, compared to other films etched duringfabrication. Such silicon oxides include, for example, thermally grownsilicon dioxide (SiO₂), TEOS, PSG, BPSG, USG (undoped spin-on-glass),LTO, etc. The need for high energies stems from the need to bombard andbreak the strong bonds of the silicon oxide films and drive chemicalreactions to form volatile etch products. These chambers are thereforereferred to as “high density oxide etch chambers,” that are capable ofproducing high plasma densities in order to provide a high ion flux tothe wafer and achieve high etch rates at low gas pressures.

[0007] While high density oxide etch chambers work well in etching thedesired wafer surfaces, the internal surfaces of the etch chamber arealso subjected to the high ion power. Therefore, material from theinternal surfaces of the etch chamber is removed as a result of the ionbombardment by either physical sputtering or chemical sputtering,depending on the composition of the material and the composition of theetch gas.

[0008] Recognizing that the internal surfaces of the etch chamber areexposed to the plasma in high density oxide chambers, chambers are nowdesigned to permit the use of simple lining parts, such as, disks,rings, and cylinders. Because these parts are configured to confine theplasma over the wafer being processed, these parts are continuouslyexposed and attacked by the processing plasma energies. Due to thisexposure, these parts ultimately erode or accumulate polymer buildup,requiring replacement or thorough cleaning. Eventually, all parts wearout to the point that they are no longer usable. These parts are hencereferred to as “consumables.” Therefore, if the part's lifetime isshort, then the cost of the consumable is high (i.e., part cost/partlifetime).

[0009] Because these parts are consumables, it is desirable to havesurfaces that are resistant to the plasma energies, which will thereforereduce the cost of the consumable. Prior art attempts to reduce the costof the consumable have included manufacturing these parts from aluminumoxide (Al₂O₃) and quartz materials. Although these materials aresomewhat resistant to the plasma energies, in high density oxide etchchambers, the high ion bombardment by the plasma has the down side ofproducing levels of contamination (e.g., particle contamination andmetallic impurity contamination) that are less than acceptable. Forexample, if the surface of the consumable part is aluminum oxide (i.e.,alumina), when the plasma bombards the surfaces, aluminum will bereleased and then will mix in with the plasma that lies above the wafer.Some of this aluminum becomes embedded in an organic polymer that isdeposited on the wafer during etching and on the surfaces of theconsumable parts (i.e., chamber liners, covers, and the like). When thishappens, the polymer on the surface of the consumable parts may not beable to be completely cleaned during a conventional in-situ plasma cleanor “ash” step. Thus, a friable, flaking film or powdery coating thatincludes C, Al, O, and F is left behind after the in-situ plasma clean,and therefore results in high particle counts. The aluminum deposited instructures being etched and the films on the silicon wafer can causedegradation of devices subsequently formed, for example, by increasingleakage current in DRAM cells.

[0010] As mentioned above, quartz is also used as the material of theinterior surfaces of the consumable parts. However, quartz surfaces havebeen found to be an unfortunate source of particles due to the lowthermal conductivity of quartz and the high etch rates in high densityplasmas used to etch oxides. Additionally, low thermal conductivityquartz makes surface temperature control of these parts very difficult.This results in large temperature cycling and flaking of the etchpolymer deposited on the surface of the consumable parts, and thereforecauses the unfortunate generation of contaminating particles. A furtherdisadvantage of quartz consumable parts is that the high etch rate inhigh density oxide etchers tends to cause pitting in the quartz, whichthen results in spalling of quartz particles.

[0011] In view of the foregoing, there is a need for high density plasmaprocessing chambers having consumable parts that are more resistant toerosion and assist in minimizing contamination (e.g., particles andmetallic impurities) of the wafer surfaces being processed. There isalso a need for consumable parts for use in high density plasmaapplications, and that are capable of withstanding temperaturevariations while preventing damage to the consumable parts.

SUMMARY OF THE INVENTION

[0012] The present invention fills these needs by providing temperaturecontrolled, low contamination, high etch resistant, plasma confiningparts (i.e., consumables) for use in plasma processing chambers. Itshould be appreciated that the present invention can be implemented innumerous ways, including as a process, an apparatus, a system, a deviceor a method. Several inventive embodiments of the present invention aredescribed below.

[0013] In one embodiment, disclosed is a plasma processing chamberincluding an electrostatic chuck for holding a wafer, and havingconsumable parts that are highly etch resistant, less susceptible togenerating contamination and can be temperature controlled. Theconsumable parts include a chamber liner having a lower support sectionand a wall that is configured to surround the electrostatic chuck. Theconsumable parts also include a liner support structure having a lowerextension, a flexible wall, and an upper extension. The flexible wall isconfigured to surround an external surface of the wall of the chamberliner, and the liner support flexible wall is spaced apart from the wallof the chamber liner. The lower extension of the liner support ishowever, configured to be in direct thermal contact with the lowersupport section of the chamber liner. Additionally, a baffle ring ispart of the consumable parts, and is configured to be assembled with andin thermal contact with the chamber liner and the liner support. Thebaffle ring defines a plasma screen around the electrostatic chuck. Aheater is then capable of being thermally connected to the upperextension of the liner support for thermally conducting a temperaturefrom the liner support to the chamber liner and the baffle ring. Alsoincluded is an outer support that is thermally connected to a coolingring that is coupled to a top plate of the chamber. The outer supportand the cooling ring are therefore capable of providing precisiontemperature control to the chamber liner, along with a cast heater. Thisprecision temperature control therefore prevents temperature drifts,which therefore advantageously enables etching a first wafer with aboutthe same temperature conditions as a last wafer.

[0014] In a most preferred embodiment, consumable parts including thechamber liner and the baffle ring are made completely from or coatedwith a material selected from silicon carbide (SiC), silicon nitride(Si₃N₄), boron carbide (B₄C) and/or boron nitride (BN) material. In thismanner, these materials, once exposed to the energy of the plasmasputtering, will produce volatile products that are substantiallysimilar to volatile etch products produced during the etching of surfacelayers of the wafer.

[0015] In another embodiment, a plasma etching chamber having consumableparts is disclosed. The consumable parts include a chamber liner havinga lower support section and a cylindrical wall that surrounds a centerof the plasma etching chamber. A liner support that is configured tosurround the chamber liner. The liner support is thermally connected tothe lower support section of the chamber liner. The liner supportfurther includes a plurality of slots that divide the liner support intoa plurality of fingers. In a preferred embodiment, the chamber liner ismade from a material selected from one of a silicon carbide (SiC)material, a silicon nitride (Si₃N₄) material, a boron carbide (B₄C)material, and a boron nitride (BN) material, and the liner support ismade from an aluminum material.

[0016] In yet another embodiment, a method for using consumable partsfor use in a high density plasma etching chamber is disclosed. Themethod includes use of a chamber liner from a material selected from oneof a silicon carbide (SiC) material, a silicon nitride (Si₃N₄) material,a boron carbide (B₄C) material, and a boron nitride (BN) material. Thechamber liner can have a wall that surrounds a plasma region of thechamber and a lower support section. The method can include use of analuminum liner support optionally having a lower extension, a flexiblewall and an upper extension wherein a plurality of slots are provided inthe flexible wall and the lower extension of the liner support to enablethe liner support to expand at elevated temperatures. The methodoptionally includes use of a baffle ring of silicon carbide (SiC),silicon nitride (Si₃N₄), boron carbide (B₄C) and/or boron nitride (BN).A plurality of slots can be provided in the baffle ring to define aplasma screen. The method can include thermal control of the chamberliner via a thermal path through the liner support and the baffle ring.

[0017] According to an embodiment of the invention, a plasma processingchamber includes a chamber liner and a liner support, the liner supportincluding a flexible wall configured to surround an external surface ofthe chamber liner, the flexible wall being spaced apart from the wall ofthe chamber liner. For purposes of optional temperature control of theliner, a heater can be thermally connected to the liner support so as tothermally conduct heat from the liner support to the chamber liner.Although any suitable materials can be used for the liner and linersupport, the liner support is preferably made from flexible aluminummaterial and the chamber liner preferably comprises a ceramic material.

[0018] The liner support can have various features. For instance, theflexible wall can include slots which divide the liner support into aplurality of fingers which enable the flexible wall to absorb thermalstresses and/or a lower extension of the liner support can be fixed to alower support section of the chamber liner. If desired, a baffle ring inthermal contact with the chamber liner and the liner support can be usedto define a plasma screen around an electrostatic chuck located in acentral portion of the chamber. The chamber liner and/or baffle ring arepreferably made from one or more of silicon carbide (SiC), siliconnitride (Si₃N₄), boron carbide (B₄C), and boron nitride (BN).

[0019] The plasma processing chamber can include various features. Forexample, the chamber liner can have low electrical resistivity and beconfigured to provide an RF path to ground. If desired, a gasdistribution plate having high electrical resistivity can be providedover an electrostatic chuck and/or a pedestal supporting a focus ringand the electrostatic chuck. The gas distribution plate, the focus ringand/or the pedestal are preferably made from one or more of the siliconcarbide (SiC), silicon nitride (Si₃N₄), boron carbide (B₄C), and boronnitride (BN). The plasma can be generated in the chamber by an RF energysource which inductively couples RF energy through the gas distributionplate and generates a high density plasma in the chamber. The RF energysource preferably comprises a planar antenna. The chamber can be usedfor plasma processing semiconductor wafers. For example, the chamber canbe a plasma etching chamber.

[0020] The liner can have various configurations. For example, the linersupport can include an outer support thermally connected to a lowerextension of the liner support and the outer support can be in thermalcontact with a water cooled top plate mounted on the chamber. The linersupport can also include an upper extension, a flexible wall, and alower extension, wherein the flexible wall and the lower extension havea plurality of slots that define a plurality of fingers in the linersupport. For temperature control, a cast heater ring can be located inthermal contact with the liner support, the heater ring including aresistance heated element which heats the liner support so as tothermally control the temperature of the chamber liner.

[0021] According to another embodiment of the invention, a semiconductorsubstrate is processed in a plasma processing chamber having a chamberliner and a liner support, the liner support including a flexible wallconfigured to surround an external surface of the chamber liner, theflexible wall being spaced apart from the wall of the chamber linerwherein a semiconductor wafer is transferred into the chamber and anexposed surface of the substrate is processed with a high densityplasma. The chamber liner is preferably a ceramic material and the linersupport preferably includes an outer support extending between the linersupport and a temperature controlled part of the chamber, the outersupport being dimensioned to minimize temperature drift of the chamberliner during sequential processing of a batch of semiconductor wafers.During wafer processing, the ceramic liner is preferably removed fromthe chamber and replaced with another ceramic liner after processing apredetermined number of semiconductor wafers. Further, the chamber linercan include a wafer entry port enabling passage of the wafer into thechamber.

[0022] Other aspects and advantages of the invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, illustrating by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings. Tofacilitate this description, like reference numerals designate likestructural elements.

[0024]FIG. 1 shows a high density plasma etching chamber in accordancewith one embodiment of the present invention;

[0025]FIGS. 2A through 2C illustrate in more detail a baffle ring inaccordance with one embodiment of the present invention;

[0026]FIG. 3A shows a more detailed cross-sectional diagram of a linersupport in accordance with one embodiment of the present invention;

[0027]FIG. 3B shows a side view of the liner support from cross sectionA-A of FIG. 3A, in accordance with one embodiment of the presentinvention;

[0028]FIG. 3C illustrates the flexibility of the liner support whensubjected to temperature stresses in accordance with one embodiment ofthe present invention;

[0029]FIG. 4 illustrates how the chamber liner is assembled with theliner support in accordance with one embodiment of the presentinvention;

[0030]FIG. 5A shows a partial cross-sectional view of the chamber liner,the liner support, and the baffle ring, assembled in accordance with oneembodiment of the present invention;

[0031]FIG. 5B shows a side view of an outer support in accordance withone embodiment of the present invention;

[0032]FIG. 6 illustrates a three-dimensional assembled view of thechamber liner, the baffle ring, and the liner support, in accordancewith one embodiment of the present invention;

[0033]FIG. 7 shows another three-dimensional view of the assembledchamber liner, liner support, and the baffle ring, in accordance withone embodiment of the present invention; and

[0034]FIG. 8 shows an exploded view of portions of the high-densityplasma etching chamber of FIG. 1 in accordance with one embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] The invention provides one or more temperature controlled, lowcontamination, high etch resistant, plasma confining parts (i.e.,consumables) for use in plasma processing chambers. In the followingdescription, numerous specific details are set forth in order to providea thorough understanding of the present invention. It will beunderstood, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process operations have not beendescribed in detail in order not to unnecessarily obscure the presentinvention.

[0036] The plasma confining parts of the present invention arepreferably in the form of, for example, chamber liners, baffle rings,gas distribution plates, focus rings, liner supports, and othernon-electrically driven parts. These parts are preferably configured tobe substantially non-contaminating and etch resistant, and they arepreferably temperature controlled without damaging the parts. The plasmaconfining parts are preferably made from materials that consist ofelements that are innocuous to devices being fabricated on the wafer,such as silicon (Si), carbon (C), nitrogen (N), or oxygen (O). In thismanner, when the plasma confining parts are bombarded by ions (i.e.,sputtered by the plasma), volatile products that combine with theprocess gases are produced. These volatile products can then be removedfrom the chamber using a vacuum pump and will not end up on the wafercausing contamination. In a preferred embodiment wherein the plasmaconfining parts are in a plasma etch chamber, such parts can be moreresistant to the etch gases and the life of the parts can be prolonged.

[0037] The plasma confining parts of the present invention arepreferably made from one or more materials such as, for example, siliconcarbide (SiC), silicon nitride (Si₃N₄), boron carbide (B₄C), and boronnitride (BN). These materials all have the desirable characteristics ofhaving high etch resistance, non-contaminating elements, and volatileetch products. In a most preferred embodiment, the plasma confiningparts (also referred to as consumable parts) are made from solid siliconcarbide (SiC), which therefore reduces metal and/or particlecontamination of the processed wafer. The SiC used for the baffle ring132 and liner 130 is preferably electrically conductive so that when itis in contact with the plasma it presents a good ground path for the RFcurrent. Higher resistivity SiC can be used for a gas distribution plate(“GDP”) (i.e., 120 of FIG. 1) in order to permit inductive coupling ofRF power through it. As mentioned above, the SiC also etches at a slowrate by the plasma making it a cost-effective consumable part.

[0038] Moreover, because the SiC is of high purity, wafer contaminationresulting from chemical sputtering of the SiC by the plasma can beminimized. Further, the grounded SiC can reduce sputtering of othersurfaces in the chamber by causing a reduction in the plasma potentialand hence ion bombardment energy to any non-silicon carbide surfaces.The SiC component also provides a very stable plasma potential so thatetch results are more repeatable within an individual chamber and fromchamber to chamber. For more information on the use of plasma confiningparts capable of reducing contamination high density plasma processing,reference may be made to a commonly assigned U.S. patent applicationhaving application Ser. No. 09/050,902, filed on Mar. 31, 1998, andentitled “Contamination Controlling Method and Apparatus For A PlasmaProcessing Chamber.” This application is hereby incorporated byreference. The various embodiments of the present invention will now bedescribed with reference to FIGS. 1 through 8.

[0039]FIG. 1 shows a high density plasma etching chamber 100 inaccordance with one embodiment of the present invention. A chamberhousing 102 is shown containing a semiconductor substrate such as asilicon wafer 104, that may be subjected to a plasma etching operation.In this embodiment, the etching operating is preferably a high densityplasma operation that is configured to etch materials such as siliconoxides, that may be formed on the surface of the wafer 104. The highdensity (e.g., plasmas having a densities between about 10¹¹-10¹²ions/cm³) plasma is established in the chamber by ensuring that thechamber is held at a relatively low pressure of below about 80 mTorr,and most preferably between about 1 mTorr and about 40 mTorr. Thepressure in the chamber is generally maintained by implementing asuitable vacuum pump at the bottom of the chamber.

[0040] The wafer 104 is shown supported over an electrostatic chuck 106.Beneath the electrostatic chuck 106 is a lower electrode 108 whichcontains a backside cooling ring 110 for controlling the temperature ofthe electrostatic chuck 106. The electrostatic chuck 106 is confined bya pedestal 112 and a focus ring 114 that surrounds the wafer 104. In oneembodiment of the present invention, the pedestal 112 and the focus ring114 are preferably made from a material selected from a group including:(a) silicon carbide (SiC), (b) silicon nitride (Si₃N₄), (c) boroncarbide (B₄C), or (d) boron nitride (BN). In a most preferredembodiment, Si₃N₄ is selected as the material for the pedestal 112 andthe focus ring 114.

[0041] According to one embodiment, an insulating alumina ring 116 sitsbetween an aluminum pedestal 118 and the lower electrode 108 and thesilicon carbide pedestal 112. A chamber liner 130 is preferably acylindrical liner which can be attached to a baffle ring 132. The bafflering 132 generally includes an inner ring 132 a that makes goodelectrical contact as well as good thermal contact with the chamberliner 130. The baffle ring 132 also has an integral array of teeth 132 bwhich will be described in greater detail with reference to FIGS. 2Athrough 2C.

[0042] Above the wafer 104 is a gas distribution plate (GDP) 120 whichfunctions as a showerhead to release the etch gas chemicals into theprocessing chamber. Above the gas distribution plate 120 sits a ceramicwindow 122. Above the ceramic window 122 is an RF coil system 120 (i.e.,an RF antenna), which is used to supply a top RF power into the reactorchamber 100. The RF coils 120 are preferably cooled via a coolingchannel that is integrated at the center of the RF coils 120. In thissimplified illustration, a gas feed port 126 is used to feed processinggases into channels that are defined between the ceramic window 122 andthe gas distribution plate 120. For more information on processchambers, reference may be made to a TCP 9100™ plasma etching reactor,which is available from LAM Research Corporation, of Fremont, Calif.

[0043] An RF impedance matching system 127 is configured to mount overthe processing chamber and make suitable contact with the RF coils 122in order to control the delivery of power as well as other reactorcontrolling parameters. As mentioned above, the ceramic window 122 isdesigned to be in contact with the gas distribution plate that mountswithin a top plate 124. The top plate 124 defines an interface betweenatmospheric pressure and a desired vacuum condition within the highdensity plasma etching chamber 100. As should be apparent to thoseskilled in the art, the desired pressure interface is established byplacing a suitable number of O-rings between interfaces of the chamberhousing 102, the top plate 124, the GDP 120, the ceramic window 122, andthe RF match system 127.

[0044] A liner support 134 is also provided within the high densityplasma etching chamber 100 to enable precision control and transfer of adesired temperature to the chamber liner 130 and the baffle ring 132. Inthis embodiment, the liner support 134 is made of aluminum to facilitateits flexibility and improve its thermal conductivity. The liner support134 includes an upper extension 134 a, a flexible wall 134 b, a lowerextension 134 c, and a liner support extension 134 d. The lowerextension 134 c is shown assembled in direct thermal contact with thechamber liner 130, and the baffle ring 132. In this embodiment, theflexible wall 134 b is slightly separated from the chamber liner 130. Aheater 140 is capable of being secured in direct thermal contact withthe upper extension 134 a of the liner support 134. To power up andcontrol the heater 140, a power connection 142 is used to couple to aheater power system 129. The liner support is therefore well suited tocontrol a desired temperature that can be thermally transferred to thechamber liner 130 and the baffle ring 132 without causing damage to the(more brittle) chamber liner 130 or baffle ring 132.

[0045] Also shown is an outer support 131, which is thermally connectedto the lower extension 134 c of the liner support 134. The outer supportis also thermally coupled to the top plate 124, which is designed toreceive a cooling ring 121. As will be described in greater detail belowwith reference to FIGS. 5A and 5B, the outer support 131 is used toachieve precision temperature control of the chamber liner 130 duringwafer processing operations (e.g., etching). The precision temperaturecontrol provided by the outer support 131 and cooling ring 121 willtherefore advantageously assist in preventing the chamber linertemperature from gradually drifting upwards (due to the plasma energies)faster than the liner's ability to radiate the heat to its surroundings.

[0046] As mentioned above, the chamber liner 130 and the baffle ring 132are preferably made of a pure silicon carbide material. In addition, thegas distribution plate 120, the focus ring 114 and the pedestal 112 arealso made of a pure silicon nitride or carbide materials, or at leastsilicon carbide coated. In this manner, substantially all of thesurfaces that confine the high density plasma will be pure siliconcarbide, or coated silicon carbide. In a broad context, other materialsthat consist only of elements that are innocuous to devices on the waferbeing processed, such as silicon (Si), carbon (C), nitrogen (N), oroxygen, which form volatile etch products with the etch gases, may beused. In this manner, the volatile products produced when the internalsurfaces that confine the plasma are bombarded, will mix with the excessetch gases that are commonly removed from the chamber (using a vacuumpump or the like). Because the products produced when the plasmabombards the internal surfaces of the chamber (i.e., the consumableparts) are volatile, these products will not end up on the surface ofthe wafer causing contamination, nor end up embedded in the polymerdeposited on the consumable parts.

[0047]FIGS. 2A through 2C illustrate in more detail the baffle ring 132in accordance with one embodiment of the present invention. As shown inFIG. 1, the baffle ring 132 functions as a plasma screen for the passageof gases and by-products to a vacuum pump connected at the bottom of thechamber 102. As shown, the baffle ring 132 has an array of teeth 132 bthat assist in maintaining the plasma in the top half of the chamber102, where the silicon carbide surfaces (of the consumables) confine theplasma substantially over the wafer 104. The baffle ring 132 also has aninner ring 132 a which is used to make good thermal contact with thechamber liner 130.

[0048]FIG. 2B is a three-dimensional view of a pair of teeth 132 b.Generally, the open areas provided by the spaces 132 c are configuredsuch that a percentage ranging between 50 and 70 percent open area ismaintained to allow a sufficient passageway for the gases andby-products to be pumped out of the chamber 102. To make each of thespaces 132 c, as shown in FIG. 2C, the solid silicon carbide material(or coated SiC material) must be machined such that a suitable aspectratio that is at least 1.5 or greater, is maintained. In this exemplaryconfiguration, the width of the spaces 132 c are preferably set to about0.13 inch, and the height is set to about 0.28 inch. These preferreddimensions therefore provide an aspect ratio of about 2.0.

[0049] The inner diameter (ID) of the baffle ring 132, in this 200 mmwafer chamber embodiment, is set to about 10.75 inches, such that about{fraction (1/16)} inch clearance is provided between the pedestal 112shown in FIG. 1. However, the inner diameter (ID) may of course belarger, depending upon the size of the wafer being processed. Forexample, for a 300 mm wafer, the inner diameter may be as large as about14 inches.

[0050] In alternative embodiments, the baffle ring 132 may bemanufactured such that the teeth 132 b are replaced with an array ofholes or slots. When an array of holes or slots are manufactured inplace of the teeth 132 b, it is still desired to maintain an open area(i.e., pathway), that amounts to between about 50 percent and 70percent. The baffle ring 132 is also shown having a plurality of screwholes 150 which are designed around the outer ring 132 a. As shown inFIG. 1, the screw holes 150 will be configured to receive a suitablescrew that will help interconnect the baffle ring 132 to the chamberliner 130 and the liner support 134. Other fasteners such as clampscould be envisioned that would supply the necessary contact force topermit sufficient heat transfer.

[0051]FIG. 3A shows a more detailed cross-sectional diagram of the linersupport 134 in accordance with one embodiment of the present invention.As mentioned above, the liner support 134 has a flexible wall 134 bwhich is configured to flex in response to heat deformation that mayoccur when the heater 140 applies the desired heat level. Preferably,the flexible wall 134 b is cylindrical and is slotted into a pluralityof fingers. As mentioned above, the liner support is preferably made ofan aluminum material which will have good thermal conductivity and willalso provide good flexibility when a desired temperature is applied bythe heater 140. Because the lower extension 134 c is bolted to thechamber liner 130 and the baffle ring 132, the lower extension 134 cwill remain in place while the upper extension 134 a, which is coupledto the heater 140 at a heat-conductive interface 141, may be able toflex outwardly as illustrated in FIG. 3C.

[0052] The heater 140 is preferably secured to the upper extension 134 ausing a suitable number of screws 144 to ensure that the heat conductiveinterface 141 is maintained all the way around the upper extension 134a. In a preferred embodiment, the screws 144 will be capable ofmaintaining the heater 140 in contact with the upper extension 134 awith a pressure of about 1,000 pounds per square inch.

[0053] When the high-density plasma etching chamber 100 is configured toprocess an 8-inch wafer (i.e., 200 mm wafer), the liner support 134 mayhave an inner diameter of about 14½ inches. The thickness 170 of theflexible wall 134 b may range between about {fraction (1/16)} inch andabout {fraction (3/32)} inch. The {fraction (1/16)} inch dimension ispreferably used for processing temperatures ranging up to about 300° C.,while the {fraction (3/32)} dimension is reserved for chambers havingprocessing temperatures up to about 1000° C.

[0054] The separation 176 between the lower extension 134 c and theupper extension 134 a is preferably set to about 2½ inches, dependingupon the chamber height. However, the greater the separation 176 is, thegreater the thermal resistance in the liner support 134. Therefore, theseparation 176 is kept just short enough such that the aluminum materialof the liner support will not become too stressed as temperatures reach300° C. and above. The exemplary thickness 172 for the upper extension134 a is preferably set to about {fraction (9/16)} inch, while theexemplary thickness of the lower extension 134 c is set to about ⅝ inch.

[0055]FIG. 3B shows a side view of the liner support 134 from crosssection A-A of FIG. 3A, in accordance with one embodiment of the presentinvention. To facilitate the flexibility of the liner support 134, slots152 are defined into the sides of the liner support 134 defining aplurality of fingers. The slots 152 vertically extend through theflexible wall 134 b and through the lower extension 134 c. Because theliner support 134 is preferably a cylindrically shaped unit, theseparation between the slots 152 must be configured such that a suitablelevel of flexibility remains in the flexible wall 134 b. Therefore, theseparation between slots 152 is preferably set to about 15 degrees.However, the actual separation between the slots 152 may vary and alsochange depending upon the diameter of the liner support 134 and thedegree of flexibility that is desired. Also shown, are the screw holes150 which are defined in the lower extensions 134 c.

[0056] To illustrate the flexibility provided by the liner support 134,FIG. 3C shows the liner support extending outwardly from a Y axis(relative to a horizontal X-axis) to achieve a separation 133. Incertain cases, the separation may be as much as {fraction (1/16)} inch,or more. Accordingly, the liner support 134 will advantageously be ableto withstand the thermal stress placed on the aluminum material of theliner support 134, while insulating the less flexible chamber liner 130and the baffle ring 132 from temperature deforming stresses.

[0057]FIG. 4 illustrates how the chamber liner 130 is assembled with theliner support 134 in accordance with one embodiment of the presentinvention. In this embodiment, when the chamber liner 130 is made ofsilicon carbide, it will provide a high integrity RF return path toground for the powered electrode 108 (bottom electrode). As is wellknown to those skilled in the art, providing a high integrity RF groundpath in the processing chamber brings the advantage of having excellentprocess repeatability. Further, the grounded SiC can reduce sputteringof other surfaces in the chamber by causing a reduction in the plasmapotential and hence ion bombardment energy on any non-silicon carbidesurfaces.

[0058] Additionally, the materials used for the chamber liner 130, suchas SiC, can have their electrical resistivity modified over a widerange. For example, the resistivity of SiC can be tailored for thespecific application. When used for the chamber liner 130 and the baffleplate 132, the SiC is modified to provide a low resistivity that willfacilitate the good conductive path to ground for the RF power. On theother hand, high resistivity is needed when the part must have RF powerinductively coupled through it, in order to minimize power dissipationin the part. Thus, high resistivity SiC is preferably used for the gasdistribution plate (GDP) 120.

[0059] As shown, the screw holes 150 are configured to go through thechamber liner 130 at a lower support section and then go into the linersupport 134. Generally, a suitable number of screws are used tointerconnect the chamber liner 130 and the liner support 134 such that agood thermally conductive interface 156 is maintained. In this manner,the heat conducted through the liner support 134 may be thermallycommunicated to the chamber liner 130 and the baffle ring 132.

[0060] In this preferred embodiment, the liner support 134 is preferablyspaced apart from the chamber liner 130 by a space 154. The space 154 ispreferably set to about {fraction (1/16)} inch. This separation isgenerally desired because the liner support 134 is configured to flex asdescribed with reference to FIG. 3C. For a 200 mm wafer chamber, adiameter 179 of the chamber liner 130 is about 14 inches. The thicknessof the chamber liner 130 is preferably set, in this embodiment, to bebetween about 0.1 inch and about 0.3 inch, and most preferably, to about0.2 inch. The height 177 of this exemplary chamber liner may be betweenabout 3 inches and about 12 inches, and most preferably about 5 inches.

[0061] Also shown is the outer support 131, which is thermally connectedto the lower extension 134 c of the liner support 134. Preferably, theouter support is spaced apart from the flexible wall 134 b so that itcan flex without substantial obstruction. The outer side of the outersupport 131 has an upper extending wall having a surface 123′, which isconfigured to make good thermal contact with the top plate 124. In thismanner, a cooling ring 121, shown in more detail in FIG. 5A, can be usedto control the temperature of the chamber liner 130 and the internalregions of the chamber. Accordingly, through the combined simultaneouscontrol of both the heater 140 and cooling ring 121, the temperature ofthe chamber liner 130 can be maintained to within less than ±10 degreesC. from a no plasma condition through a sustained plasma on condition.Thus, the first wafer etched can be etched with the same chamber liner130 temperature as the last wafer etched, to within the ±10 degrees C.variation.

[0062]FIG. 5A shows a partial cross-sectional view of the chamber liner130, the liner support 134, and the baffle ring 132 assembled inaccordance with one embodiment of the present invention. As shown, thechamber liner 130 and the liner support 134 are assembled to achieve agood thermal conductive interface 156 as described above.

[0063] As mentioned above, the outer support 131 is thermally connectedto the lower extension 134 c through a plurality of screws 135. Theouter support 131, in a most preferred embodiment, has a flexible wall131 a, which is shown to be thermally connected to the top plate 124. Aside view of the outer support 131 is also provided in FIG. 5B, toillustrate how a plurality of fingers 131 d, separated by a plurality ofslots 131 c, assist in providing the necessary flexibility to theflexible wall 131 a. The top plate 124 is further configured to receivethe cooling ring 121 on a top lip of the top plate 124. Of course, otherconfigurations for applying the cooling ring 121, or other type ofcooling system, to the top plate 124 may be used.

[0064] In this embodiment, the combined use of the heater 140 and thecooling ring 121 will enable precision temperature control in narrowtemperature ranges. For example, the chamber liner 130 is typically runat high temperatures, such as 200 degrees C. or more, while heat is lostto the surroundings primarily through radiation. When plasma isinitiated, the plasma dumps more heat into the chamber liner 130 by ionbombardment. The chamber liner 130 will slowly increase in temperatureover time because it generally cannot transfer this heat to itssurroundings by radiation as fast as it gains heat from the plasma.Thus, the outer support 131, which is thermally coupled to the coolingring 121, is well suited to eliminate the chamber liner's temperaturedrift. In this embodiment, the heat loss to the outer support 131 fromthe liner support 134 can be set by adjusting the cross-section andlength of the outer support 131. This adjustment, can therefore be madeto control the heat loss path from the liner support 134 to thetemperature controlled top plate 124.

[0065] As shown, the chamber liner 130 will also provide a good thermalconductive interface 157 with the baffle ring 132. To achieve this goodconductive interface, the baffle ring 132, the chamber liner 130, andthe liner support 134 are secured together using a plurality of screws150′. Preferably, the screws 150′ are fitted through a spacer ring 131 bwhich is in direct contact with the inner ring 132 a of the baffle ring132, a spacer 131 a′, and the chamber liner 130.

[0066] The spacer ring 131 b and the spacer 131 a′ are preferably madeof aluminum and provide a good surface for applying pressure to thescrews 150′ and the brittle surfaces of the baffle ring 132 and thechamber liner 130. That is, because the baffle ring 132 is preferably aceramic, applying too greater of a force with screws directly to thebaffle ring may cause a crack in the baffle ring or the chamber liner130. Once the screws 150′ are secured all the way around the chamber,the chamber liner, the baffle ring and the liner support (i.e., theconsumable parts) will be ready for use in the high density plasmaetching chamber 100 of FIG. 1. As used herein, these parts are referredto as consumable parts, however, when silicon carbide (or otheralternative materials described herein) is used for the parts thatconfine the high density plasma, these parts will have a longerlifetime, and therefore, a lower cost of consumables.

[0067] When replacement is needed, these parts may be swiftly replacedwith replacement parts (i.e., using a quick clean kit). Because theliner support 134 is not designed to be in contact with the high densityplasma, it may not wear out as fast as the chamber liner 130 and thebaffle ring 132. Thus, the liner support 134 may be removed from wornout consumable parts (that may be cleaned off-line and re-used ordiscarded), and then used with the replacement consumable parts. Whenthe chamber is being used in fabrication where chamber down timetranslates into lower yields, the ability to quickly replace theseconsumables will have the benefit of reducing the mean time to clean thechamber.

[0068]FIG. 6 illustrates a three-dimensional assembled view of thechamber liner 130, the baffle ring 132, and the liner support 134, inaccordance with one embodiment of the present invention. As shown, thetop surface of the upper extension 134 a of the liner support 134, isconfigured with a plurality of screw holes that will receive the heater140. Along the walls of the liner support 134 are the plurality of slots152 that define fingers configured to flex in response to temperaturevariations. A wafer entry port 160 is defined in the wall of the chamberliner 130 to enable the passage of a wafer into and out of the chamber100. Typically, the wafer is preferably passed into the chamber using arobot arm which must partially fit into the port 160, and release thewafer once over the electrostatic chuck 106. Therefore, the port 160should be large enough to receive the wafer and robot arm, but alsomaintained small enough to not disrupt the plasma profile over thewafer. As shown in FIG. 7, an insert with a slot in the shape of theport 160 is attached to the outside of the liner. Like the otherconsumable parts, the insert can be of SiC, Si₃N₄, B₄C and/or BN.

[0069] The liner support 134 typically also includes through holes 162which are also defined in the chamber liner 130. The through holes 162may include holes for probing the pressure within the chamber duringprocessing, and for optically detecting the endpoint in a particularprocess. Also shown with greater detail are plurality of holes 161 whichare used to receive the screws 144 for holding down the heater 140 tothe upper extension 134 a of the liner support 134.

[0070]FIG. 7 shows another three-dimensional view of the assembledchamber liner 130, liner support 134, and the baffle ring 132. From thisview, the port hole 160 used for passing a wafer to the electrostaticchuck 106, is shown in greater detail. Also shown are the teeth 132 b ofthe baffle ring 132. The teeth 132 b therefore extend in close proximityto the pedestal 112 to screen the plasma from the lower part of thechamber as shown in FIG. 1.

[0071]FIG. 8 shows an exploded view of portions of the high-densityplasma etching chamber 100 of FIG. 1 in accordance with one embodimentof the present invention. This view shows the spacer ring 131 b that isused in the assembly of the baffle ring 132, the chamber liner 130, andthe liner support 134. This perspective also illustrates how the heater140 is applied over the top extension 134 a of the liner support 134.The heater 140, as shown, is preferably a cast heater. Of course, othertypes of heating systems may also work. When the heater 104 isappropriately secured, a good thermal contact will be made with theliner support 134.

[0072] The power connection 142 is also shown, which will be passedthrough a hole 124 a in the top plate 124. The top plate 124 is showncapable of receiving the gas distribution plate 120. The gasdistribution plate 120 has channels 120 a which enable processing gasesfed by gas feed ports 126 to be directed into the chamber 100. Althoughnot shown in this example, the ceramic window 122 may then be loweredover the gas distribution plate 120.

[0073] In a preferred embodiment of the present invention, the highdensity plasma etch chamber 100 is particularly well suited to etchsilicon oxide materials, such as, for example, thermally grown silicondioxide (SiO₂), TEOS, PSG, BPSG, USG (undoped spin-on-glass), LTO, etc.,while reducing the introduction of unwanted contaminants. For exemplarypurposes only, to achieve the high density plasma conditions in thechamber 100, the pressure within the chamber is preferably maintainedbelow about 80 mTorr, and the RF coil 128 (i.e., top electrode) ispreferably set to between about 2500 watts and about 400 watts, and mostpreferably to about 1,500 watts. The bottom electrode 108 is preferablymaintained between about 2500 watts and about 700 watts, and mostpreferably at about 1,000 watts. In typical high density oxide etchprocesses, process gases such as, CHF₃, C₂H₅ and/or C₂F₆ are introducedinto the chamber to generate the desired etching characteristics.

[0074] As mentioned previously, the materials that can be used for theplasma confining parts (e.g., the consumables, including the chamberliner 130, the baffle ring 132, the GDP 120, the focus ring 114, and thepedestal 112) are generally innocuous to layers being fabricated on thewafer 104. That is, volatile etch products that result from etching thesurfaces of the wafer 104 will be similar to the volatile productsproduced when the consumables are bombarded (i.e., sputtered) with theplasma energies. As an advantageous result, these volatile productsproduced from ion bombardment of the consumables will join the normalvolatile etch products.

[0075] This therefore facilitates the removal of these combined volatileproducts from the internal region of the chamber 100 through the use ofa vacuum pump that connects to the chamber. Due to the fact that thevolatile products from the consumables are able to be expeditiouslyremoved from the wafer processing region, substantially fewer levels ofparticulates and metallic contaminants will interfere with the devicesbeing fabricated on the surface of the wafer 104. While this inventionhas been described in terms of several preferred embodiments, it will beappreciated that those skilled in the art upon reading the precedingspecifications and studying the drawings will realize variousalterations, additions, permutations and equivalents thereof. Therefore,although specific details are provided with respect to reducingcontamination for semiconductor wafers, such benefits may also apply toflat panel display substrates, and the like. Furthermore, although apreferred material for the consumable parts is pure silicon carbide(SiC), the material may also be a SiC coated material such as SiC coatedgraphite, or principally SiC with 10 to 20% Si added to fill porosity inreaction bonded SiC. As also mentioned previously, the consumable partsmay also be made from materials such as, silicon nitride (Si₃N₄), boroncarbide (B₄C), and boron nitride (BN). These materials all have thedesirable characteristics of having high etch resistance,non-contaminating elements, and volatile etch products.

[0076] It is therefore intended that the present invention include allsuch alterations, additions, permutations, and equivalents as fallwithin the true spirit and scope of the invention.

What is claimed is:
 1. A plasma processing chamber having a chamberliner and a liner support, the liner support including a flexible wallconfigured to surround an external surface of the chamber liner, theflexible wall being spaced apart from the wall of the chamber liner. 2.A plasma processing chamber as recited in claim 1, further comprising aheater thermally connected to the liner support so as to thermallyconduct heat from the liner support to the chamber liner.
 3. A plasmaprocessing chamber as recited in claim 1, wherein the liner support ismade from flexible aluminum material and the chamber liner comprises aceramic material.
 4. A plasma processing chamber as recited in claim 3,wherein the flexible wall includes slots which divide the liner supportinto a plurality of fingers which enable the flexible wall to absorbthermal stresses.
 5. A plasma processing chamber as recited in claim 4,wherein a lower extension of the liner support is fixed to a lowersupport section of the chamber liner.
 6. A plasma processing chamber asrecited in claim 1, further comprising a baffle ring in thermal contactwith the chamber liner and the liner support, the baffle ring defining aplasma screen around an electrostatic chuck located in a central portionof the chamber.
 7. A plasma processing chamber as recited in claim 6,wherein the baffle ring is made from one or more of silicon carbide(SiC), silicon nitride (Si₃N₄), boron carbide (B₄C), and boron nitride(BN).
 8. A plasma processing chamber as recited in claim 1, wherein thechamber liner is made from one or more of silicon carbide (SiC), siliconnitride (Si₃N₄), boron carbide (B₄C), and boron nitride (BN).
 9. Aplasma processing chamber as recited in claim 1, wherein the chamberliner has low electrical resistivity and is configured to provide an RFpath to ground.
 10. A plasma processing chamber as recited in claim 1,further comprising a gas distribution plate defining over anelectrostatic chuck, the gas distribution plate having high electricalresistivity.
 11. A plasma processing chamber as recited in claim 10,wherein the gas distribution plate is made from one or more of siliconcarbide (SiC), silicon nitride (Si₃N₄), boron carbide (B₄C), and boronnitride (BN).
 12. A plasma processing chamber as recited in claim 1,further comprising a focus ring and a pedestal supporting the focus ringand an electrostatic chuck.
 13. A plasma processing chamber as recitedin claim 12, wherein the focus ring and the pedestal are made from oneor more of silicon carbide (SiC), silicon nitride (Si₃N₄), boron carbide(B₄C), and boron nitride (BN).
 14. A plasma processing chamber asrecited in claim 1, further comprising a focus ring, a pedestal, and/ora gas distribution plate made from one or more of silicon carbide (SiC),silicon nitride (Si₃N₄), boron carbide (B₄C), and boron nitride (BN).15. A plasma processing chamber as recited in claim 11, furthercomprising an RF energy source which inductively couples RF energythrough the gas distribution plate and generates a high density plasmain the chamber.
 16. A plasma processing chamber as recited in claim 1,wherein the RF energy source comprises a planar antenna.
 17. A plasmaprocessing chamber as recited in claim 1, wherein the liner supportfurther includes an outer support thermally connected to a lowerextension of the liner support, the outer support being in thermalcontact with a water cooled top plate mounted on the chamber.
 18. Aplasma processing chamber as recited in claim 1, wherein the chamber isa plasma etching chamber.
 19. A plasma processing chamber as recited inclaim 1, wherein the liner support includes an upper extension, aflexible wall, and a lower extension, wherein the flexible wall and thelower extension have a plurality of slots that define a plurality offingers in the liner support.
 20. A plasma processing chamber as recitedin claim 1, wherein a cast heater ring is in thermal contact with theliner support, the heater ring including a resistance heated elementwhich heats the liner support so as to thermally control the temperatureof the chamber liner.
 21. A method of processing a semiconductorsubstrate in the plasma processing chamber as recited in claim 1,wherein a semiconductor wafer is transferred into the chamber and anexposed surface of the substrate is processed with a high densityplasma.
 22. The method of processing a semiconductor substrate asrecited in claim 21, wherein the chamber liner is a ceramic material andthe liner support includes an outer support extending between the linersupport and a temperature controlled part of the chamber, the outersupport being dimensioned to minimize temperature drift of the chamberliner during sequential processing of a batch of semiconductor wafers.23. The method of processing a semiconductor substrate as recited inclaim 21, wherein the chamber liner is a ceramic liner which is removedfrom the chamber and replaced with another ceramic liner afterprocessing a predetermined number of semiconductor wafers.
 24. A plasmaprocessing chamber as recited in claim 1, wherein the chamber linerincludes a water entry port enabling passage of the wafer into thechamber.